Multidrug resistance proteins and topoisomerase IIalpha expression in colon cancer: association with metastatic potential

Evaluation of P-glycoprotein (Pgp) expression in human osteosarcoma by high-throughput tissue microarray

Survival of osteosarcoma patients is currently limited by the development of metastases and multidrug resistance (MDR). A well-established cause of MDR involves overexpression of P-glycoprotein (Pgp) in tumor cells. However, some discrepancies still exist as to the clinical significance of Pgp in osteosarcoma. We sought to elucidate further whether the Pgp expression correlated with clinical behavior in a series of patients with osteosarcoma via high-throughput tissue microarray (TMA) analysis. Immunohistochemical analysis of Pgp expression in a TMA of 114 specimens with a retrospective review of 70 osteosarcoma patients admitted to the Massachusetts General Hospital (MGH) was performed. High Pgp expression was correlated with metastasis development and poor response to pre-operative chemotherapy in osteosarcoma patients. Eighteen of the fifty-seven patients initially admitted with primary osteosarcoma showed high Pgp expression. Among these 18 patients with high Pgp expression, 13 of 18 (72%) patients eventually developed metastases. There was no significant clinical relevance between Pgp expression and osteosarcoma survival. These results support that high expression of Pgp is important, but cannot be assigned as, an individual predictor in the development of human osteosarcoma. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1606-1612, 2016.

Clinical Implications and Future Perspectives of Circulating Tumor Cells and Biomarkers in Clinical Outcomes of Colorectal Cancer

Colorectal cancer (CRC) is a major public health problem. Early CRC detection, pretherapeutic responsiveness prediction, and postoperative micrometastasis monitoring are the hallmarks for successful CRC treatment. Here, the methodologies used for detecting circulating tumor cells (CTCs) from CRC are reviewed. In addition to the traditional CRC biomarkers, the persistent presence of posttherapeutic CTCs indicates resistance to adjuvant chemotherapy and/or radiotherapy; hence, CTCs also play a decisive role in the subsequent relapse of CRC. Moreover, the genetic and phenotypic profiling of CTCs often differs from that of the primary tumor; this difference can be used to select the most effective targeted therapy. Consequently, studying CTCs can potentially individualize treatment strategies for patients with CRC. Therefore, CTC detection and characterization may be valuable tools for refining prognosis, and CTCs can be used in a real-time tumor biopsy for designing individually tailored therapy against CRC.

Twist mediates an aggressive phenotype in human colorectal cancer cells

Epithelial-mesenchymal transition (EMT) is a crucial process providing cancer cells with the ability to migrate and metastasize to distant sites. Recently, EMT was shown to be associated with the cancer stem cell (CSC) phenotype and chemoresistance. Twist is a transcription factor that regulates EMT in a various cancer cells, including colorectal cancer (CRC). Our study was done to determine the role of Twist in mediating aggressive phenotype in CRC. Human CRC cell lines were transduced with a retroviral Twist construct or vector control. Migration and invasion abilities were determined in vitro using modified Boyden chamber assays. Mammosphere formation assay was performed to detect CSC characteristics. EMT and CSC markers were detected using western blotting and RT-PCR. Chemosensitivity to oxaliplatin of the transfected cells were determined by the MTT assay. Human CRC specimens were stained for Twist and P-gp expression. Twist overexpression triggered EMT and a CSC-like phenotype in human CRC cells and enhanced cell migration, invasion and mammosphere formation abilities. In addition, Twist-overexpressing CRC cells were more chemo-resistant to oxaliplatin than control cells. Furthermore, Twist over-expression increased P-gp expression in CRC cells, which is a transmembrane glycoprotein conferred multidrug-resistance phenotype to various cancer cells. Importantly, Twist and P-gp were expressed correlatively in human CRC specimens. Thus, Twist is a potential therapeutic target in metastatic CRC.

Circulating tumor cells as a surrogate marker for determining clinical outcome to mFOLFOX chemotherapy in patients with stage III colon cancer

BACKGROUND

This study was aimed to detect post-chemotherapeutic circulating tumour cells (CTCs) in stage III colon cancer patients and identify those who were at high risk of relapse.

METHODS

We used human telomerase reverse transcriptase, cytokeratin-19, cytokeratin-20, and carcinoembryonic antigen (CEA) as the biomarkers to detect CTCs in 90 stage III colon cancer patients undergoing curative resection followed by mFOLFOX chemotherapy.

RESULTS

Post-chemotherapeutic relapse occurred in 30 (33.3%) patients. By univariate analysis and multivariate proportional hazards regression analysis, perineural invasion (hazard ratio (HR): 2.752; 95% confidence interval (CI): 1.026-7.381), high post-chemotherapeutic serum CEA levels (HR: 2.895; 95% CI: 1.143-7.333) and persistent presence of post-chemotherapeutic CTCs (HR: 6.273; 95% CI: 2.442-16.117) were independent predictors of post-chemotherapeutic relapse. In addition, the persistent presence of post-chemotherapeutic CTCs strongly correlated with reduced disease-free survival and overall survival. Accuracy of detecting relapse in post-chemotherapeutic stage III colon cancer patients by analysing the persistent presence of post-chemotherapeutic CTCs was higher than that by post-chemotherapeutic CEA levels (odds ratio: 50.091 vs 5.211).

CONCLUSION

The persistent presence of post-chemotherapeutic CTCs is a potential powerful surrogate marker for determining clinical outcome in stage III colon cancer patients receiving adjuvant mFOLFOX chemotherapy.

Proliferation-inhibiting and apoptosis-inducing effects of ursolic acid and oleanolic acid on multi-drug resistance cancer cells in vitro

OBJECTIVE

To investigate the proliferation-inhibiting and apoptosis-inducing effects of ursolic acid (UA) and oleanolic acid (OA) on multi-drug resistance (MDR) cancer cells in vitro.

METHODS

UA and OA in different concentrations (0-100 μmol/L) were added separately to cultures of different cancer cell lines, including the human colon cancer cell lines SW480 and SW620, human acute myelocytic leukemia cancer cell lines HL60 and HL60/ADR, human chronic myelogenous leukemia cell lines K562 and K562/ADR, and the human breast cancer cell lines MCF-7 and MCF-7/ADR. Effects of UA and OA on cell proliferation were detected by 3-(4,5-dimethyl-2-thiazole)-2-5-biphenly-tetrazole bromide (MTT) method and effects on cell apoptosis were tested by flow cytometry (FCM) and Western blot at 24, 48, and 72 h after treatment.

RESULTS

Both UA and OA showed significant inhibition on parent and MDR cell lines in a time- and concentration-dependent manner; the drug-resistant multiple of them on K562 and K562/ADR as well as on HL60 and HL60/ADR was 1; the effects of UA were better than those of OA in inhibiting cell growth of solid colonic cancer and breast cancer. After SW480 cells were treated by UA at the concentrations of 0-40 μmol/L for 48 h, FCM showed that annexin V (AV) positive cells and hypodiploid peak ratio increased along with the increase in the drug's concentrations; and Western blot found that expressions of Bcl-2, Bcl-xL and survivin decreased in a concentration-dependent manner.

CONCLUSIONS

Both UA and OA have antitumor effects on cancer cells with MDR, and the optimal effect is shown by UA on colonic cancer cells. Also, UA shows cell apoptosis-inducing effect on SW480, possibly by way of down-regulating the expressions of apoptosis antagonistic proteins, Bcl-2, Bcl-xL, and survivin.

Increased topoisomerase IIalpha expression in colorectal cancer is associated with advanced disease and chemotherapeutic resistance via inhibition of apoptosis

Topoisomerase IIalpha is a nuclear enzyme that regulates the tertiary structure of DNA. The influence of topoisomerase IIalpha gene (TOP2A) or protein alterations on disease progression and treatment response in colorectal cancer (CRC) is unknown. The study investigated the clinical relevance of topoisomerase IIalpha in CRC using in vivo and in vitro models. Differentially expressed genes in early and late-stage CRC were identified by array comparative genomic hybridization (CGH). Cellular location of gene amplifications was determined by fluorescence in situ hybridization (FISH). Topoisomerase IIalpha levels, proliferation index, and HER2 expression were examined in 228 colorectal tumors by immunohistochemistry. Overexpression of topoisomerase IIalpha in vitro was achieved by liposome-based transfection. Cell growth inhibition and apoptosis were quantified using the crystal violet assay and flow cytometry, respectively, in response to drug treatment. Amplification of TOP2A was identified in 3 (7.7%) tumors using array CGH and confirmed using FISH. At the protein level, topoisomerase IIalpha staining was observed in 157 (69%) tumors, and both staining and intensity levels were associated with an aggressive tumor phenotype (p values 0.04 and 0.005, respectively). Using logistic regression analysis, topoisomerase IIalpha remained significantly associated with advanced tumor stage when corrected for tumor proliferation (p=0.007) and differentiation (p=0.001). No association was identified between topoisomerase IIalpha and HER2. In vitro, overexpression of topoisomerase IIalpha was associated with resistance to irinotecan (p=0.001) and etoposide chemotherapy (p=0.03), an effect mediated by inhibition of apoptosis. Topoisomerase IIalpha overexpression is significantly associated with alterations in tumor behavior and response to drug treatment in CRC. Our results suggest that gene amplification may represent an important mechanism underlying these changes.

Topoisomerase I and IIalpha protein expression in primary colorectal cancer and recurrences following 5-fluorouracil-based adjuvant chemotherapy

Purpose

Human DNA topoisomerases I and II (topo-I and -II) are essential for vital cellular processes such as DNA replication, transcription, translation, recombination, and repair. In the present study, we correlate topo-I and -II expression and outcome after chemotherapy in primary and relapsed colorectal cancer.

Patients and methods

Patients with colorectal cancer that had recurred, following surgery and adjuvant chemotherapy and underwent a second operation were included in the present study. All had undergone surgical resection of the primary tumor and received post-operatively 5-FU-based (5FU + Leucovorin, Mayo Clinic regimen) adjuvant chemotherapy. Tumor tissue was collected at the initial operation from the primary tumor and at the time of recurrence (during the second operation following chemotherapy). All tissue samples were analyzed for levels of expression of both topo-I and topo-IIa using standard three-step immunohistochemistry on paraffin sections.

Results

Forty patients were included. Levels of expression of topo-I and topo-II were higher in malignant cells from tumor recurrences compared to primary tumors (P = 0.0001 for both). There was a statistically significant positive relationship between patients age and levels of topo-I (P = 0.011) and topo-II (P = 0.011) expression.

Conclusions

The study results reported here underscore the role of topoisomerase expression in colorectal cancer and suggest a potential role in tumor recurrence.

Crucial role of interleukin-4 in the survival of colon cancer stem cells

Colon tumors may be maintained by a rare fraction of cancer stem-like cells (CSC) that express the cell surface marker CD133. Self-renewing CSCs exhibit relatively greater resistance to clinical cytotoxic therapies and recent work suggests that this resistance may be mediated in part by an autocrine response to the immune cytokine interleukin 4 (IL-4). Blocking IL-4 signaling can sensitize CSCs to apoptotic stimuli and increase the in vivo efficacy of cytotoxic therapy. These findings suggest that inhibitors of IL-4 signaling may offer a new therapeutic tool in colon carcinoma.

Topoisomerase IIalpha in Wilms' tumour: gene alterations and immunoexpression

BACKGROUND

Topoisomerase IIalpha (topoIIalpha) is an essential enzyme gene in regulating DNA structure and cell proliferation and is encoded by the TOP2A. Using cDNA microarray analysis, TOP2A has been reported to be one of the top genes overexpressed in Wilms' tumour.

AIM

To evaluate the role of TopoIIalpha in Wilms' tumorigenesis and its prognostic value.

METHODS

TOP2A gene copy numbers were determined using the fluorescence in situ hybridisation technique, and protein expression levels of TopoIIalpha by immunostaining in 39 samples of primary and 18 samples of metastatic Wilms' tumour.

RESULTS

TOP2A gene amplification was detected only in anaplastic Wilms' tumours, and none of the Wilms' tumours showed deletion of the TOP2A gene. TopoIIalpha protein overexpression was detected in 97% of Wilms' tumours, and correlated strongly with proliferation, as measured by Ki-67 (r = 0.85). The high TopoIIalpha expression was associated with the presence of vascular invasion, prominent apoptosis, metastases and adverse clinical outcomes (p<0.05).

CONCLUSIONS

Our findings suggest that TopoIIalpha overexpression in Wilms' tumours is caused by a change at the transcription level, except for anaplastic Wilms' tumours, in which gene amplification was present. High levels of TopoIIalpha protein are correlated with tumour aggressiveness. The assessment of TopoIIalpha expression in Wilms' tumour may have prognostic value.

The CD44 receptor interacts with P-glycoprotein to promote cell migration and invasion in cancer

Invasion and metastases of cancer cells and the development of resistance to anticancer therapies are the main causes of morbidity and mortality from cancer. For more than two decades, these two important but not clearly related aspects in the biology of cancer have been extensively studied. Specifically, P-glycoprotein and CD44 have been characterized and are known to be determinants of multidrug resistance (MDR) and metastases. Despite this body of knowledge, few reports have linked the two phenotypes and only recently have there been reasons to suspect a direct connection. In this report, we show that a novel physical and genetic interaction between CD44s and P-glycoprotein is in part responsible for the correlation between MDR and invasive potential in cancer cells. P-glycoprotein-specific substrates that interfere with its function reduced in vitro invasion, migration, and the physical colocalization of CD44s and P-glycoprotein. CD44 expression in sensitive cells promoted the expression of P-glycoprotein and the MDR phenotype. RNA interference of MDR1 inhibited the rate of cell migration. These data indicate that there is a close interaction between CD44 and P-glycoprotein that results in the concurrent expression and modulation of two malignant phenotypes, invasion and MDR.